Note: Descriptions are shown in the official language in which they were submitted.
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SAFETY ARRANGEMENT IN A PACKAGE TURNING DEVICE
TECHNICAL FIELD
The present ittvention relates to a safety arrangement in a package turning
device of the type which turns selected packages which are conveyed on a
conveyor
path, the package turning device comprising a piston and cylinder assembly
with a piston rod disposed to move parallel with the conveyor path, a turning
member and a gripping member.
BACKGROUND ART
Fackage turning devices of the type which turn selected packages being
conveyed on a conveyor path are employed, for example, for turning one of the
packages in a multipack in order, by such means, to conceal the bar code
carried on
the package_ The bar code on each package contains, int. al_ Information on
the price
of the- individual package and when the package is included in a multipack,
this
multipack will have a new bar code which indicates the price of the multipack
unit.
For example, the multipack may contain two or more individual packages,
Multipacks are often employed for single-use disposable packages of small
volume for liquid foods, such as juices and fruit drinks. These single-use
disposable
packages are- manufactured from a packaging laminate with a core layer of
paper or
paperboard to which are laminated different layers of thermoplastic and
possibly
aluminium foil (Alifoil). The packaging material, which most generally occurs
in
web form, is formed in a filling machine into a tube and is longitudinal-
sealed. The
tube is filled with the intended contents, whereafter it is transversely
sealed and
severed in the seals to form individual packaging blanks. The packaging blanks
are
finally formed and normally obtain a parallelepipedic configuration.
With filling machines which are developed to work-at increasingly higher
capacity, it is a requirement that the distribution equipment, such as package
turning
devices, which normally accompany a filling machine have the same capacity.
When
the finished packages depart from the filling machine, they are conveyed on a
conveyor path and in order to avoid the accumulation of packages, a turning
device
(where applicable) must be able to carry out the turning operation of selected
packages while the packages pass along the conveyor path.
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Turning devices for packages of the above-outlined type are available on the
market and they generally consist of a pneumatic or hydraulic piston and
cylinder
assembly, with a reciprocating movement which is parallel with the conveyor
path on
which the packages are being conveyed. On the piston rod of the assembly,
there is
disposed a turning member as well as members for gripping the package. Turning
devices of this type are well-known to those skilled in the art.
However, it has proved that a piston and cylinder assembly of a size which is
suitable for executing the turning operation does not possess sufficient
accuracy as
regards adapting the speed of the piston rod to the conveyor path so that the
gripping
member can grip the package in the correct position. If the package is not
gripped
centrally, there is a risk that the package is overturned and thrown outside
the
conveyor path, or that it topples over and causes disruption in the
distribution
equipment. Piston and cylinder assemblies of this size have moreover proved to
be
sensitive to the environment in which they are placed. In the event of
disruption in
the distribution equipment, there is always the risk that the packages are
ruptured and
that the product sloshes or sprays out in its surroundings. Since the product,
normally
juices and fruit drinks, contains sugar, the result will be a tacky surface on
those parts
of the distribution equipment which have been subjected to product sloshing.
One method of solving this problem is naturally to employ a piston and
cylinder assembly which is considerably more robust. By employing a more
robust
assembly, a higher degree of accuracy will be obtained for the movement of the
assembly in relation to the conveyor path, and a more robust assembly is also
more
resistant to the environment in which it is to operate. However, the
employment of a
more robust piston and cylinder assembly entails that the risk of damage to
the
package proper and the equipment increases when there is a sudden operational
stoppage in the distribution equipment. It must therefore be ensured that the
machine
stops immediately when this occurs. Operational stoppage may, for example, be
because the movement of the gripping member is prevented in that packages
topple
over or that a foreign object intervenes.
OBJECTS OF THE INVENTION
One object of the present invention is to realise a safety arrangement which
is
triggered rapidly and distinctly.
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A further object of the present invention is that it should not contain
components which are sensitive to the environment in which the arrangement is
placed.
SOLUTION
These and other objects have been attained accordinc, to the present invention
in that an arranbement of the type described by way of introduction has been
given
the characterising features that the safety arrangement includes an anchorage
disposed on the piston rod of the piston and cylinder assembly, and a bracket
which
is disposed to support the turning member and the gripping member, the
anchorage
and the bracket being united in spring-biased fashion so that they enclose a
cavity,
and that an incoming air conduit and an outgoing air conduit are connected to
the
cavity, with a pressure guard disposed on the outgoing air conduit.
Broadly then in one aspect, the invention provides a safety arrangement in
a package turning device of the type which turns selected packages which are
conveyed on a conveyor path, the package turning device comprising a piston
and
cylinder assembly with a piston rod disposed to move parallel with the
conveyor
path, a turning member and a gripping member, wherein the safety arrangement
includes an anchorage disposed on the piston rod of the piston and cylinder
assembly, and a bracket which is disposed to support the turning member and
the
gripping member, the anchorage and the bracket being united in spring-biased
fashion so that they enclose a cavity, and wherein an incoming air conduit and
an
outgoing air conduit are connected to the cavity, with a pressure guard
disposed
on the outgoing air conduit.
Preferred embodiments of the present invention have further been given the
characterising features as set forth in the appended subclaims.
BRiEF DESCRIPTION OF THE ACCOMPANYING DRAWLVGS
One preferred embodiment of the present invention will now be described in
greater detail hereinbelow, with particular reference to the accompanying
Drawings..
In the accompanying Drawings:
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Fig. I shows a package turning device of the type with which the arrangement
according to the present invention may be employed;
Fig. 2 is a side elevation of a package turning device in normal operational
position;
Fig. 3 is a side elevation of a package turning device in the evertt of an
operational stoppaae;
Fig. 4 is a side elevation of the gripping member in a closed position;
Fig. 5 is a side elevation of the gripping member in an open position; and
Figs, 6A-E show the operational sequence of the package turning device,
The accompanying Drawings show only those details essential to an
understanding of the present invention.
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DESCRIPTION OF PREFERRED EMBODIMENT
The safety arrangement according to the present invention is intended to be
employed for a package turning device of the type which is shown in Figs. 1-6.
The
turning device is intended to turn selected packages I. The packages I may be
single-
use disposable packages of the type which is employed for juices and fruit
drinks of
various types. The packages I are filled and formed in a filling machine (not
shown)
and they may, as shown, display a parallelepipedic configuration. After the
filling
machine, the packages I are conveyed on a conveyor path 2. The path 2 may
consist
of a conventional conveyor, such as a driven, endless chain. The conveyor path
2
runs through the package turning device, or alternatively a system of
different paths.
The package turning device essentially comprises a piston and cylinder
assembly 3, a turning member 4 and a gripping member 5. In the preferred
embodiment of the present invention, the piston and cylinder assembly 3 is
pneumatic. Alternatively, the assembly 3 may be hydraulic. The piston and
cylinder
assembly 3 is mounted such that its piston rod 6 may reciprocate parallel with
the
conveyor path 2. The forward-going movement of the piston rod 6 is adapted so
that
it moves forward at the same speed as the conveyor path 2. In that the piston
and
cylinder assembly 3 is overdimensioned in relation to the work it is to carry
out,
increased control capability is obtained, which makes it easier to adapt the
speed of
the piston rod 6 to the speed of the conveyor path 2. The service life of the
assembly
3 is also considerably increased in that the more robust assembly 3 is
considerably
more resistant to the environment in which it works.
An anchorage 7 is mounted on the piston rod 6. A bracket 8 is mounted
against the anchorage 7. The anchorage 7 and the bracket 8 are united in
spring-
biased fashion by means of springs 9. The turning member 4 with the gripping
member 5 is mounted on the bracket 8.
Between the spring-biased, united anchorage 7 and the bracket 8, there is a
small cavity 10. The cavity 10 may be disposed either in the anchorage 7 or
alternatively in the bracket 8. The cavity 10 may also be formed so that it is
accommodated in both anchorage 7 and bracket 8. The anchorage 7 and the
bracket 8
are mounted such that the cavity 10 is enclosed in the normal operation of the
package turning device, when the anchorage 7 and the bracket 8 are held
together by
means of the springs 9.
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Two apertures 11, 12 are provided to the cavity 10. The one aperture 11 is
connected to an incoming air conduit 13, while the other aperture 12 is
connected to
an outgoing air conduit 14. The incoming air conduit 13 is connected to a
source of
compressed air (not shown). A regulator (not shown) is also provided on the
incoming air conduit 13 so that the incoming air may be regulated to a desired
level.
A pressure guard (not shown) is provided on the outgoing air conduit 14. The
pressure guard is suitably placed outside the package turning device, in a dry
and
benign environment.
In the preferred embodiment of the present invention, the regulator on the
incoming air conduit 13 is set at 0.5 bar. Levels below 0.5 bar require a
specific and
more expensive pressure guard. Levels above 0.5 bar may also be employed and,
by
omitting the regulator, the compressed air can be connected directly to the
aperture
11. But the greater the excess pressure of the incoming air, the more powerful
must
be the springs 9 so as to hold together the anchorage 7 and the bracket 8
under
normal operation.
The one aperture 11 to the cavity 10 is powerfully throttled to a diameter of
approx. 2 mm. The incoming air conduit 13 must be mounted to this aperture 11.
In
order to avoid the risk of incorrectly fitting the air conduits 13 and 14, the
second
aperture 12 may also be throttled since it does not affect the function of the
safety
arrangement.
The work cycle of the package turning device is apparent from Figs. 6A-E.
Just ahead of the package turning device, there is disposed a conventional
brake 15
which ensures that the packages I arrive in the turning device with uniform
spacing
between the packages 1. The Drawings show a turning device which is disposed
to
turn every third package 1 which is advanced on the conveyor path 2.
In Fig. 6A, the packages 1 which are marked with numbers 1 and 2 have
passed out from the brake 15 and continue along the path 2. Just after the
brake 15,
some form of indicator (not shown) is disposed, such as photocells, which are
operative to count the number of packages I passing.
The gripping member 5 has two gripping claws 16 which are movable
between an open and a closed position. The package I carrying number 3 is
gripped
by the gripping member 5 in that its gripping claws 16 clamp against the side
of the
package 1 as shown in Fig. 4. It is vital that the gripping claws 16 grasp the
package
I centrally so that the turning operation is smooth. If the gripping claws 16
grip at
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one edge of the package 1, there is a risk that the package I is thrown around
in the
turning operation and that the package I risks toppling over. The gripping
claws 16
are terminated by rounded holders 17 in order that the package 1 is being
handled in
as gentle a manner as possible.
In Fig. 6B, the piston rod 6 of the piston and cylinder assembly 3 has moved
along and at the same speed as the conveyor path 2, at the same time as the
package
I which is held fast in the gripping claws 16 is turned through 180 . The
package 1 is
turned, without being lifted, so that it is constantly in contact with the
conveyor path
2.
Fig. 6C shows the end position of the turning member 4 and the gripping
member 5. Here, the gripping claws 16 are opened as shown in Fig. 5 and the
turned
package 1 is released in order to continue on the conveyor path 2. In Fig. 6D,
the
piston rod 6 returns to its starting position. During the entire return
movement, the
gripping claws 16 are in the open position in order that those packages 1
which have
been passed on the way back are not disrupted in their movement. Fig. 6E shows
the
gripping member 5 back in its starting position ready to grip the new package
I
which is marked with number 3.
After the packages I have departed from the turning device with every third
package I turned through 180 , the packages I continue on the conveyor path 2
to
further distribution equipment. Such distribution equipment may, for example,
consist of a shrink film wrapper, where the packages 1, three-by-three, are
surrounded by a shrink or stretch film to form a multipack.
Both Figs. 6A-E and Fig. 2 show the package turning device in normal
operation. If a toppled package I or a foreign object intervenes, the gripping
claws
16 will be subjected to a force A as shown in Fig. 3. The force A may impinge
on the
gripping claws 16 both from the front, from behind or from the side, depending
upon
the movement of the piston rod 6 and what has caused the force A. The gripping
member 5 is mounted in the turning member 4 and the turning member in the
bracket
8, so that the force A tips all of these components as a unit. As a result, a
slight air
gap 18 occurs between the anchorage 7 and the bracket 8.
Since the excess pressure in the cavity 10 is regulated to 0.5 bar, a very
slight
gap is required for air to bleed out and the pressure in the outgoing air
conduit 14
falls to zero. Since the aperture 11 into the cavity 10 is powerfully
throttled to a
diameter of approx. 2 mm, the area of the gap 18 will rapidly exceed the area
of the
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throttle and the air pressures falls almost instantaneously. The pressure
guard
registers the pressure drop and emits a signal to the control system of the
package
turning device which immediately stops the package turning device. By having a
rapid and distinct signal, the movement of the piston rod 6 is quickly
arrested and
damage to both packages 1 and equipment is reduced.
By employing air for indicating a disruption in the operation of the package
turning device, there will be obtained a safety arrangement which includes no
sensitive electric components. The pressure guard which is required and the
pressure
regulator which is provided in the preferred embodiment may be placed in a
space
where they do not run the risk of being sprayed with sugary product.
As will have been apparent from the foregoing description, the present
invention realises a safety arrangement which, in a simple and reliable
manner,
immediately gives a signal to the package turning device to stop the movement
of the
piston rod in the event of a sudden operational stoppage. Since the
arrangement does
not include any sensitive or expensive components, a safety arrangement will
be
obtained which is relatively economical and which has a high expected service
life.
The present invention should not be considered as restricted to that described
above and shown on the Drawings, many modifications being conceivable without
departing from the scope of the appended Claims.
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